1819.] Prof. Leslie on Heat and Climate. 5 



American science as the earliest original purely scientific journal 

 of America. 



Dr. Bruce had, in a high degree, the feelings of a man of 

 science. He was ever forward to promote its interests, and both 

 at home and abroad was considered as one of its most distin- 

 guished American friends. 



Many strangers of distinction came introduced to him, and 

 his urbanity and hospitality rarely left him without guests at his 

 board. During the latter part of his life, he seems to have been 

 Jess interested in science. His journal had been so long sus- 

 pended, that it was considered as virtually relinquished ; his 

 health was undermined by repeated attacks of illness ; and 

 science and society had to lament his sudden departure, when 

 he had scarcely attained the meridian of life. 



He died in his native place on Feb. 22, 1818, of an apoplexy, 

 in the 41st year of his age. 



Article II. 



Vn Heat and Climate* By John Leslie, Esq. Professor of 

 Mathematics in the University of Edinburgh. 



The word heat is of ambiguous import, and signifies either a 

 certain sensation, or the external cause of that sensation. In 

 this latter sense, considered as an attribute or accident of matter, 

 heat forms an interesting subject of physical inquiry. Curiosity 

 prompts us to consider in what its nature consists. Is it a state 

 or condition of bodies, or is it a peculiar substance which, by its 

 union with them, communicates certain properties ? Some philo- 

 sophers hold it to consist in the intestine motion of particles, 

 and allege, in confirmation of their doctrine, that it is always 

 excited by percussion. The chemists, on the other hand, have 

 inclined to the supposition of an igneous fluid, and their opinion 

 is now almost universally adopted. The former hypothesis 

 indeed can hardly furnish any solid argument in its support. 

 When a ball is struck, the tremor soon glows languid, and dies 



* This early performance was read at two several meetings of the Royal Society 

 of London, as far back as February or March, 1793. It was not, however, ad- 

 mitted into the Transactions of that learned body, but retained and deposited in 

 their archives. Fortunately I had preserved some notes, from which I was enabled 

 soon after to complete the copy ; and at the distance of twenty-six years, I am now 

 induced to draw the paper from oblivion, and to communicate it to the public 

 through the independent medium of a respectable philosophical journal. With 

 all its imperfections, the essay will be found to contain not only the rudiments of 

 my subsequent researches, but to open some original views which, even in the 

 present state of science, must, unless I am greatly mistaken, be deemed new. It 

 will besides ascertain the priority of certain discoveries with the history of wbicb 

 'lie public is unacquainted. 1 have, therefore, printed the text exactly as it stood, 

 ;ind only subjoined a few remarks and corrections. — Author. 



